This section provides background information related to the present disclosure which is not necessarily prior art. This section further provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Radio detection and ranging (radar) is used to sense angle, range and velocity of (moving) scatterers in the environment. Radar sensor capabilities of merit include maximum range and solid angle, as well as angular, range and velocity resolution. Range and velocity are typically detected through pulse delay ranging and the Doppler effect (pulse-Doppler), or through the frequency modulated continuous wave (FMCW) technique and range differentiation. Angle is detected by scanning the volume with a highly directive beam. Scanning is done mechanically, by rotating an antenna, or electronically, by steering the beam of an array. Angular resolution typically depends on the beamwidth of the antenna or the array, but techniques such as monopulse significantly increase the angular resolution of pulse-Doppler radars beyond real beamwidth. The range resolution is limited by the instantaneous signal bandwidth of the radar sensor in both pulse-Doppler and FMCW radars.
According to principles of the present teachings, a radar system comprising an orthogonal frequency division multiplexing (OFDM) modem and a frequency scanning antenna is provided. The OFDM modem produces an OFDM modulation. The frequency scanning antenna then radiates the OFDM modulated radio frequency (RF) energy. Directionality of the frequency scanning radar is dependent upon the sub-band carrier frequency of the OFDM modulation.
In some embodiments, the radar system further comprises a transmit/receive (T/R) module that up-converts and amplifies the OFDM modulation, and outputs the amplified signal to the frequency scanning antenna. In some embodiments, the T/R module amplifies and down-converts a received RF signal from the frequency scanning antenna and outputs the down-converted signal to the OFDM modem. A plurality of scanning angles can be measured simultaneously.
In some embodiments, the frequency scanning antenna comprises a slotted waveguide, which is traveling-wave fed. In some embodiments, the slotted waveguide comprises at least one of a helical and a serpentine (also called sinuous or meandered) waveguide feed. Slots of the slotted waveguide can be milled from a broad wall or the narrow wall of the slotted waveguide. Slots of the slotted waveguide can also be linearly aligned or offset. In some embodiments, slots of the slotted waveguide are tapered in width for uniform amplitude excitation of the slotted waveguide.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.